The inventor is a co-author of the following paper: "Glycerol Kinetics With Parenteral Lipid Emulsions (LCT, MCT and SL) in Rats", D. Drews, M. D. Schluter and T. P. Stein, Metabolism, 42:743-748 (1993).
The present invention relates to food products containing partially hydrogenated structured lipids. More particularly, these food compositions possess valuable properties as a high energy food source for the military and for athletes who have a need for a palatable and convenient food source with a high caloric density.
In the past, numerous high energy food compositions have been proposed which have met with varying degrees of success. Most are saccharide-based and contain high levels of simple and complex carbohydrates. These tend to provide the consumer with what is perceived as an energy boost. However, the compositions, as a source of energy, have little advantage over a normal diet, or the contents of a normal diet given at a similar level of hydration.
The present invention utilizes materials known as "partially hydrogenated structured lipids", or PHSLs, as an extremely high source of calories as the energy source of the composition. "Partially hydrogenated structured lipids" are structured lipids which have been subjected to food-grade hydrogenation processes, resulting in a product having a lower degree of unsaturation than the starting structured lipid.
While structured lipids have been extensively utilized as a food source for patients which are severely compromised, e.g., burn patients, these compositions have limitations which make them unsuitable for the requirements of athletes and the military.
Babayan, et al., U.S. Pat. No. 4,952,606, issued on Aug. 28, 1990, relates to a dairy fat containing structured lipid composition. The composition is reported to show unexpected nutritional benefits.
Babayan, et al., U.S. Pat. No. 4,847,296, issued on Jul. 11, 1989 relates to a structured lipid composition which can be administered enterally for patients undergoing severe metabolic stress, such as surgical burn patients.
Bistrian, U.S. Pat. No. 5,081,105, issued on Jan. 14, 1992 relates to a method of treating cancer using structured lipids and other agents, such as tumor necrosis factor.
Bistrian, et al., U.S. Pat. No. 4,871,768, issued on Oct. 3, 1989 relates to structured lipids containing omega 3 fatty acids and medium chain fatty acids.
Bistrian, et al., U.S. Pat. No. 4,810,726, issued on Mar. 7, 1989 relates to a lipid emulsion containing medium and long chain triglycerides.
Blackburn, U.S. Pat. No. 4,528,197, issued on Jul. 9, 1985 relates to the used of structured lipids in hypercatabolic mammals. The composition involves a mixture of medium and long chain fatty acids, and is reported to provide more than 60% of the total caloric requirements of the mammal without immunological impairment.
Simko, U.S. Pat. No. 4,690,820, issued Sep. 1, 1987, relates to a high caloric, high fat dietary composition having an increased proportion of fat, which is utilizable for enteral hyperalimentation of critically ill patients.
None of the references noted above disclose a composition which is convenient and palatable, and which can be used as a major source of calories for short period of time by individuals who are healthy and essentially uncompromised. The present invention involves the administration of a food product containing partially hydrogenated structured lipids to a mammal to provide a source of energy. Typically, such mammals are those such as athletes and the military who require a food product providing a high level of usable calories, for purposes of training or during a particular athletic event, such as marathon running, or a food source which can be utilized during mobile activities, such as military maneuvers, where convenience and compactness is required.
The structured lipids utilized in the treatment of patients in abnormal metabolic stress states induced by trauma or sepsis are not suitable sources of nutrition for athletes or the military since they are in a normal or "uncompromised" state.
The structured lipids that have been designed for clinical use, especially those to be administered parenterally, are based on vegetable oils high in polyunsaturateds, particularly linoleic acid, where it is necessary to prevent essential fatty acid deficiency from developing. The mechanism of essential fatty acid depletion is that continuous feeding of high glucose regimens leads to essential fatty depletion in the non-adipose tissues. But the high plasma insulin levels inhibit lipid mobilization from the adipose tissues (where there is plenty of linoleic acid) and so the non-adipose tissues rapidly (within 7-14 days) become depleted of the essential fatty acids. With normal eating patterns, the plasma insulin levels drop at night and after the post-absorptive phase. Between meals and at night, plasma insulin levels drop. This allows normal lipid mobilization and replenishment of linoleate in the depleted tissues. Therefore, uncompromised patients with normal feeding patterns of meals and snacks, this problem does not arise.
It is necessary to maximize the available energy content to support metabolism--as opposed to the theoretical energy content of the lipid. The theoretical energy content is the maximal amount of energy that can be obtained from the lipid by bomb calorimetry. The available energy is the amount of energy available to support tissue energy requirements after the digestion, absorption and processing of the lipid have been accomplished. The use of lipids high in polyunsaturateds is thus contra-indicated.
First, the utilization of triglycerides rich in linoleic acid such as those derived from safflower, soybean, sunflower and other vegetable oils waste energy in their metabolism. Specifically, there is increased substrate cycling with these lipids (Drews et al., Metabolism, supra). Up to 20% of the energy content of the triglyceride can be wasted with such substrate cycling. The administered lipid after digestion and absorption is then taken up by the liver and adipose tissue, modified via hydrolysis and reesterification (TG-FFA cycling) and then either stored or oxidized. The more linoleic acid in the triglyceride, the greater the cycling. The cycling occurs because of the physiological need to regulate free linoleic-arachidonic acid levels due to their roles are precursors of prostaglandins. Thus, lipolysis of triglycerides rich in linoleic acid releases unacceptably high levels of linoleic acid on hydrolysis. To prevent this from becoming a problem, the linoleic content of the triglycerides is reduced by mixing them with endogenous triglycerides. The process is known as Triglyceride-Free Fatty Acid (TG-FFA) cycling. Thus, in a conventional triglyceride emulsion derived from soybean oil and labeled with .sup.14 C given to dogs, 60% of the label is still in the dog 24 hours later (see Metabolism paper, supra). The source of the fat oxidized on giving a mixture high in such triglycerides is the equilibrated triglyceride. In order to provide the maximum amount of usefully usable calories, the lipid formulation should not include as a major component, fatty acids which stimulate this TG-FFA cycling.
Secondly, the administration or ingestion of a high concentration of linoleic and other polyunsaturated fatty acids has been shown to result in activation of the arachidonic acid--prostaglandin pathway which can lead to an exaggerated response to stress. Thus, in a food product for athletes or the military, as a high energy calorie source, this would be a serious disadvantage. An exacerbated response to injury is highly undesirable for troops under field conditions where they may well be injured.
Accordingly, it is an object of the present invention to provide a food product formed of partially hydrogenated structured lipids which provide a convenient and palatable food source while meeting the specialized nutritional high energy requirements of athletes and the military.
A still further object is to provide a composition which can be formulated with a minimum amount of water or other liquid contained therein.
Another object is to provide a composition which can be readily transported by the individual during a particular athletic event or other endeavor, with the individual during training, or transported on its own.
These and other objects and features of the invention will be apparent to those of ordinary skill from the following description.